1. Technical Field of the Invention
The present disclosure relates generally to oxygen concentrators. More particularly, the present disclosure relates to an improved portable apparatus for concentrating and delivering high pressure oxygen to a ventilator.
2. Description of the Related Art
A wide range of clinical conditions may require some form of ventilation therapy. These conditions may include hypoxemia, various forms of respiratory insufficiency, and airway disorders. There are also non-respiratory and non-airway diseases that require ventilation therapy, such as congestive heart failure and neuromuscular diseases.
To improve the quality of life of many patients who require long-term ventilation therapy, ventilation systems have been developed which are miniaturized and portable. Some of these systems, for example, the NIOV system by Breathe Technologies, Inc., are so lightweight and compact that they are wearable by the patient. However, these systems also require a source of pressurized ventilation gas to operate, which is usually oxygen. One option for patients is the use of pressurized oxygen cylinders.
Improvements in battery technology have made it feasible for patients to use portable oxygen concentrators instead of pressurized oxygen cylinders with portable ventilators. Portable oxygen concentrators typically operate by pressure swing adsorption, in which ambient air is pressurized by a compressor and passed through an adsorbent sieve bed. The sieve bed is typically formed of zeolite, which preferentially adsorbs nitrogen when at high pressure while oxygen passes through. Once the sieve bed reaches its capacity to adsorb nitrogen, the pressure can be reduced. This reduction in pressure causes the adsorbed nitrogen to be desorbed so it can be purged, leaving a regenerated sieve bed that is again ready to adsorb nitrogen. With repeated cycles of this operation, an enriched oxygen gas may be generated. Typically, portable oxygen concentrators have at least two sieve beds so that at one may operate while the other is being purged of the nitrogen and vented.
Portable oxygen concentrators have a cost and convenience advantage over pressurized oxygen cylinders, due to the pressurized oxygen cylinders requiring ongoing refilling or replacement. Additionally, portable oxygen concentrators are considered to be significantly safer than pressurized oxygen cylinders. This safety consideration can have a substantial impact on a patient's quality of life as well, because many portable oxygen concentrators have been approved by the FAA for use by travelers on commercial airlines during flight, whereas personal filled oxygen cylinders are universally banned. Consequently, patients with pressurized oxygen cylinders must make expensive and time-consuming preparations with an airline ahead of time, or forego airline travel entirely.
However, despite their shortcomings, pressurized oxygen cylinders have certain advantages over portable oxygen concentrators, particularly as they relate to performance. In particular, while the pressure and rate of oxygen flow from pressurized oxygen cylinders can be adjusted to meet virtually any pressure and flow rate a patient's ventilator may requires, either continuously or periodically, conventional portable oxygen concentrations are limited in this regard, and typically do not produce enriched oxygen gas at the pressures required for some ventilator systems. Additionally, while conventional portable oxygen concentrators are capable of producing an enriched oxygen gas with a purity of around 87-96% oxygen, oxygen cylinders can output substantially pure oxygen.
In view of the foregoing, there is a need in the art for an improved portable oxygen concentrator.